166 Ittinois NaturAL History SurvEY BULLETIN 
yellow-brown, shading to yellow at lateral 
margins and, usually, at ends of outer parap- 
sides; scutellum yellow; semimembranous 
area anterior to base of fore wing shaded 
with rose-pink; pleuron yellow, an oblique, 
black streak ventral to base of fore and 
hind wings; sternum yellow; fore leg tan or 
deep yellow, apex of tibia black, first tarsal 
segment two-fifths to three-fifths as long as 
second segment; middle and hind legs yel- 
low; each femur of all legs with a median 
and an apical, dark brown crossband ; wings 
hyaline, stigmatic area of fore wing very 
slightly stained with brown, veins yellow- 
brown, crossveins very dark brown or black, 
veins and crossveins of hind wing yellow, 
outer wing margin shaded. Abdomen yellow, 
a black crossline at posterior margin of each 
tergite 1-8; spiracular marks present; apical 
three tergites shaded with orange-brown, 
sometimes with a rosy flush added; genitalia, 
fig. 337, light yellow; caudal filaments gray- 
yellow, articulations brown. 
NympH.—Length of body 9-10 mm. Head 
anterior to compound eyes uniform brown, 
with a pale spot on anterior margin at 
meson and a lateral, pale spot on this mar- 
gin anterior to each antennal socket; large, 
pale spots lateral to eyes. Thoracic notum 
mostly uniform brown, pronotum usually 
pale at lateral and posterior margins, and 
mesonotum pale on meson in anterior half; 
tarsal claws without ventral denticles. Ab- 
domen dorsally mostly dark brown, a row of 
elongate, pale spots present on either side of 
the dorsal meson on tergites +10, some- 
times these pale spots almost continuous; 
each sternite 1-9 with a pair of sublateral, 
brown spots, these spots more elongate and 
extending nearly the length of the segment 
on posterior two or three sternites, posterior 
margin of ninth sternite either entirely pale 
or faintly shaded with brown; caudal fila- 
ments light brown. 
This species is known from Illinois, Ken- 
tucky, Massachusetts, Minnesota, and On- 
tario. 
Illinois Records. — Benton: at light, 
June 10, 1946, H. H. Ross, 1g. Kanxka- 
KEE: June 6, 1935, Ross & Mohr, 1¢. 
Momence: Aug. 16, 1938, Ross & Burks, 
24. Pavisapes State Park: at light, June 
16, 1948, Stannard & Smith, 1%. WavukeE- 
GAN: Aug. 15, 1938, Ross & Burks, 2¢. 
Wuite HeatrH: Aug. 2, 1940, Ross & 
Riegel, 12. 
Vol. 26, Art. 1 
8. Stenonema interpunctatum (Say) 
Baetis inter punctata Say (1839:41). 
Stenonema interpunctatum interpunctatum 
(Say). Spieth (1947:106). 
Mave.—Length of body 7-9 mm., of fore 
wing 8-10 mm. Head yellow, face with 
prominent, black marks ventral to antennal 
sockets, vertex shaded with orange-brown; 
compound eyes in life light green; each an- 
tennal scape and pedicel yellow, flagellum 
gray-brown at base, becoming hyaline toward 
apex. Mesonotum dark yellow-brown; yel- 
low at lateral margins, at posterior ends of 
outer parapsides, and on scutellum; semi- 
membranous area anterior to base of fore 
wing yellow or flesh colored; each pleuron 
yellow, a gray-brown oblique streak present 
ventral to fore wing base, also, sometimes, 
ventral to hind wing base; sternum yellow; 
fore leg deep yellow, tibia black at apex, 
first fore tarsal segment from one-fourth to 
one-third as long as second segment; middle 
and hind legs light yellow; front and middle 
femora each with a median and an apical, 
dark brown crossband, hind femur with only 
apical band; wings hyaline, stigmatic area of 
fore wing faintly stained with brown, veins 
yellow-brown, crossveins dark brown or 
black; veins and crossveins of hind wing 
yellow, outer margin shaded with black. 
Abdomen yellow, posterior margin of each 
tergite 1-8 with a narrow, black cross-stripe; 
spiracular markings absent; apical three ter- 
gites shaded with pink- or orange-tan; geni- 
talia, fig. 338, yellow; caudal filaments gray- 
yellow to almost hyaline, articulations not, 
or only obscurely, darkened. 
NympH.—Length of body 8-10 mm. 
Head anterior to compound eyes uniform 
brown, anterior margin without light spots; 
relatively small, pale spots on margins lat- 
eral to eyes. Dorsum of thorax mostly uni- 
form brown; pronotum with a pair of sub- 
lateral and a pair of anterolateral, pale 
spots, the latter sometimes extending along 
part or all of lateral pronotal margin; longi- 
tudinal, pale stripe on meson of anterior 
half of mesonotum; tarsal claws without 
ventral denticles. Gills borne by first six 
abdominal segments pointed at apexes, each 
gill of seventh pair with one trachea; dor- 
sum of abdomen brown, a pair of subme- 
dian, longitudinal, pale streaks on each of 
tergites 1-9, these forming an almost con- 
tinuous pair of stripes, usually of uniform 
